Apparatus for receiving compressed digital information

ABSTRACT

An apparatus for receiving digital information including a receiver which receives the digital information that has digital video information bit-compressed by a first compression system, digital audio information bit-compressed by a second compression system, and error-detection information added to both the digital video information and the digital audio information. There is also provided a demodulator which demodulates the digital information received by the receiver, an error detector which detects an error of digital information demodulated by the demodulator by use of the error-detection information, a first expander which bit-expands video information among the digital information error detected by the error detector corresponding system, and a second expander which bit-expands audio information among the digital information error detected by the error detector corresponding to the second compression system.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. application Ser. No. 11/305,229, filedDec. 19, 2005, now U.S. Pat. No. 7,027,240, which is a continuation ofU.S. application Ser. No. 10/404,452, filed Apr. 2, 2003, now U.S. Pat.No. 7,012,769, which is a continuation application of U.S. applicationSer. No. 10/277,830, filed Oct. 23, 2002, now U.S. Pat. No. 6,590,726,which is a continuation of U.S. Ser. No. 09/809,047, filed Mar. 16,2001, now U.S. Pat. No. 6,498,691, which is a continuation applicationof U.S. application Ser. No. 09/654,962, filed Sep. 5, 2000, now U.S.Pat. No. 6,324,025, which is a continuation of U.S. Ser. No. 09/567,005,filed May 9, 2000, now U.S. Pat. No. 6,278,564, which is a continuationapplication of U.S. Ser. No. 09/326,595, filed Jun. 7,1999, now U.S.Pat. No. 6,069,757, which is a continuation of U.S. application Ser. No.09/188,303, filed Nov. 10, 1998, now U.S. Pat. No. 6,002,536, which is acontinuation of U.S. application Ser. No. 08/917,176, filed Aug. 25,1997, now U.S. Pat. No. 5,862,004, which is a continuation of U.S.application Ser. No. 08/620,879, filed Mar. 22, 1996, now U.S. Pat. No.5,699,203, and copending with U.S. application Ser. No. 08/620,880,filed Mar. 22, 1996, now U.S. Pat. No. 5,673,154, which arecontinuations of U.S. application Ser. No. 08/457,597, filed Jun. 1,1995, now U.S. Pat. No. 5,530,598, which is a continuation of U.S.application Ser. No. 08/457,486, filed Jun. 1, 1995, now U.S. Pat. No.5,517,368, which is a continuation of U.S. application Ser. No.08/238,528, filed May 5,1994, now U.S. Pat. No. 5,671 ,095, which is adivisional of U.S. application Ser. No. 07/727,059, filed Jul. 8, 1991,now U.S. Pat. No. 5,337,199, the subject matter of which areincorporated by reference herein. This application relates to U.S. Ser.No. 11/305,052, filed Dec. 19, 2005.

BACKGROUND OF THE INVENTION

The present invention relates to a system for transmitting a digitalvideo signal and recording the received video signal. More particularly,the present invention relates to great extension of the range of use ofa digital signal recording/reproducing system by greatly shortening arecording time through transmission of a video signal in a compressedform, and further relates to great extension of the range of use of adigital signal recording/reproducing system by making the number ofsignals to be recorded and a recording/reproducing time variable.

As a digital magnetic recording/reproducing system (hereinafter referredto as VTR) is conventionally known, for example, a D2 format VTR. Insuch a conventional digital VTR, the elongation or shortening of areproducing time is possible by using variable-speed reproduction.However, the prior art reference does not at all disclose high-speedrecording in which a recording time is shortened to 1/m, multiplerecording in which a plurality of signals are recorded, and thecompression/expansion of a recording/reproducing time.

The above-mentioned conventional digital VTR has a feature that a highquality is attained and there is no deterioration caused by dubbing.However, the shortening of a dubbing time is not taken intoconsideration. Therefore, for example, in the case where a two-hourprogram is to be recorded, two hours are required. Thus, there is adrawback that inconveniences are encountered in use. Also, themultiplexing of recording signals is not taken into consideration.Therefore, for example, when two kinds of programs are to besimultaneously recorded or reproduced, two VTR's are required. This alsocauses inconveniences in use.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a digital VTR in whichhigh-speed recording onto a tape can be made with the same format asthat used in standard-speed recording, to provide a transmission signalprocessing system for transmitting at a high speed a video signal to berecorded by such a digital VTR, and to extend the range of use of thedigital VTR by shortening a recording time. For example, the digital VTRcan be used in such a manner that a two-hour program is recorded inabout ten minutes and is reproduced at a standard speed.

The above object is achieved as follows. A video signal and an audiosignal are subjected to time-base compression to 1/m, bit compression to1/n, addition of a parity signal and modulation, and are thereaftertransmitted or outputted. The transmitted signal is received, issubjected to demodulation, error correction, addition of a parity signaland modulation, and is thereafter recorded, onto a magnetic tape whichtravels at a travel speed m times as high as that upon normalreproduction, by use of a magnetic head on a cylinder which rotates at afrequency m times as high as that upon normal reproduction. The signalon the magnetic tape traveling at a travel speed upon normalreproduction is reproduced by a magnetic head on the cylinder whichrotates at a frequency upon normal reproduction. The reproduced signalis subjected to demodulation, error correction, bit expansion of videoand audio signals and D/A conversion, and is thereafter outputted.Address signals corresponding to a plurality of VTR's may be transmittedprior to a signal to be recorded. Further, control signals indicative ofthe start of recording and the stop of recording may be transmitted. Thetransmitted signals are received and error-corrected, and controls ofthe standby for recording, the start of recording and the stop ofrecording are made on the basis of the control signals.

With the above construction, since the video signal and the audio signalare time-base compressed to 1/m and bit-compressed to 1/n, atransmission time is shortened to 1/m and a signal band turns to m/n.The time-base compressed and bit-compressed signal is transmitted afteraddition of a parity signal for error correction and modulation to acode adapted for a transmission path. The transmitted signal is receivedand demodulated. The detection of an error produced in a transmittingsystem and the correction for the error can be made using the addedparity signal. The error-corrected signal is added with a parity signalfor correction for an error produced in a magnetic recording/reproducingsystem and is modulated to a code adapted for the magneticrecording/reproducing system. Upon recording, since the rotationfrequency of the cylinder and the travel speed of the magnetic tape areincreased by m times, the recording onto the magnetic tape can be madeat an multiple speed. Upon reproduction, by setting the rotationfrequency of the cylinder and the travel speed of the magnetic tape tonormal ones, the reproduction at a normal speed can be made. Thereproduced signal is code-demodulated. The detection of an errorproduced in the magnetic recording/reproducing system and the correctionfor the error can be made on the basis of the parity signal. Bybit-expanding the video signal and the audio signal compressed by thetransmission signal processing system, the original video and audiosignal can be restored. The bit-expanded signal is converted into ananalog signal by a D/A converter. Simultaneous and selective control ofthe start/stop of recording for a multiplicity of VTR's can be made insuch a manner that the address signals corresponding to the VTR's aretransmitted prior to a signal to be recorded, the correction for anerror of the received signal is made, required VTR's are brought intorecording standby conditions by the corrected address signals, and thecontrols of the start of recording and the stop of recording are made bythe transmitted control signals.

Another object of the present invention is to provide a digital signalrecording/reproducing system in which multiple recording onto a tape canbe made with the same format as that used in standard recording andsimultaneous multiple reproduction is possible, and to extend the rangeof use of a digital VTR by compressing/expanding a recording/reproducingtime in accordance with the transmission rate of a multiplexedinput/output signal and the number of signals in the multiplexedinput/output signal.

This object is achieved as follows. There are provided means forselecting one or plural desired signals from a time-base compressed andtime-division multiplexed digital input signal, and helical scanrecording means for making time-division multiplex recording of theselected signals with a time-base compressed speed after selection beingretained. There is further provided means for reproducing the recordedsignals with the rotation speed of a cylinder, a tape speed and so onbeing set to values proportional to the transmission rate of areproduction signal and the number of signals to be simultaneouslyreproduced and with the signal being time-base expanded or beingretained as time-base compressed.

With the above construction, N kinds of desired signals selected fromthe multiplexed input digital signal and time-base compressed to 1/K aresubjected to time-division multiplex recording with a time-basecompressed speed after selection being retained. Upon reproduction, forexample, if both the cylinder rotation speed and the tape speed are setto N/K times, a recording track and a reproducing track coincide witheach other and the use of a reproducing time K/N times as long as arecording time enables the reproduction of each of the N kinds ofsignals at a standard speed. Also, if both the cylinder rotation speedand the tape speed are set to (M×N)/K times, a recording track and areproducing track coincide with each other and the use of a reproducingtime as K/(M×N) times as long as the recording time enables thereproduction of each of the N kinds of signals at an M-tuple speed. Inthe case where L kinds of signals are selected from among the N kinds ofreproduced signals and a processing speed at a reproduction signalprocessing circuit is set to L×M times as long as a standardreproduction processing speed, each of the L kinds of signals among theN kinds of multiple-recorded signals is outputted at a speed M times ashigh as a standard speed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a digital transmission signal processingsystem and a recording/reproducing system according to an embodiment ofthe present invention;

FIG. 2 is a block diagram of a recording/reproducing system according toanother embodiment of the present invention;

FIG. 3 is a diagram for explaining the conventional parity addingmethod;

FIG. 4 is a block diagram of a recording/reproducing system according tostill another embodiment of the present invention;

FIG. 5 is a block diagram of a digital transmission signal processingsystem and a recording/reproducing system according to a furtherembodiment of the present invention;

FIG. 6 shows the format of control signals used in one of applicationsof the present invention;

FIG. 7 is a block diagram of a still further embodiment of the presentinvention;

FIG. 8 shows one example of the specification of signals to be recorded;

FIG. 9 is a block diagram of a furthermore embodiment of the presentinvention;

FIGS. 10, 11 and 12 are block diagrams of different examples ofapplications of the present invention;

FIG. 13 is a block diagram for explaining one example of the operationof the embodiment shown in FIG. 7;

FIG. 14 is a timing chart showing the waveforms of signals involved inthe example shown in FIG. 13;

FIG. 15 is a block diagram for explaining another example of theoperation of the embodiment shown in FIG. 7;

FIG. 16 is a timing chart showing the waveforms of signals involved inthe example shown in FIG. 15;

FIG. 17 is a table showing some applications of the examples shown inFIGS. 13 and 15;

FIG. 18 is a block diagram of a still furthermore embodiment of thepresent invention; and

FIGS. 19 and 20 are signal diagrams for explaining different operationsof the embodiment shown in FIG. 18.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

An embodiment of the present invention will now be explained by use ofFIG. 1. In the figure, reference numerals 1 and 40 denote magnetictapes, numerals 2, 3, 41 and 42 magnetic heads, numerals 4 and 43cylinders, numerals 5 and 44 capstans, numerals 10 and 50 servo controlcircuits, numerals 20, 31 and 60 demodulation circuits, numerals 21, 32and 61 error correction circuits, numerals 22 and 23 compressioncircuits, numerals 24 and 33 parity addition circuits, numerals 25 and34 modulation circuits, numerals 26 a transmission circuit, numeral 27 atransmission path, numeral 30 a reception circuit, numerals 62 and 63expansion circuits, numerals 64 and 65 D/A conversion circuits, numeral70 a video signal output terminal, and numeral 71 an audio signal outputterminal.

Firstly, the operation of a transmission signal processing system willbe explained. Digital video and audio signals recorded on the magnetictape 1 are reproduced by the magnetic heads 2 and 3 mounted on thecylinder 4 and are inputted to the demodulation circuit 20. The magnetictape 1 travels by virtue of the capstan 5. The travel speed of themagnetic tape 1 and the rotation frequency of the cylinder 4 are, forexample, ten times as high as the tape travel speed and the cylinderrotation speed upon normal reproduction. Accordingly, the signalinputted to the demodulation circuit 20 is a signal time-compressed toone tenth. For example, a 120-minute signal recorded on the magnetictape 1 can be reproduced in 12 minutes.

Generally, in the case where a digital signal is to be recorded on amagnetic recording medium, the signal is recorded after having beenmodulated into scrambled NRZ code, M² code or the like. The demodulationcircuit 20 performs a demodulation processing, that is, a signalprocessing for restoring the thus modulated signal into original digitaldata. The signal demodulated by the demodulation circuit 20 is inputtedto the error correction circuit 21 in which erroneous data produced in amagnetic recording/reproducing process is detected and the correctionfor the erroneous data is made. Further, the signal is separated into avideo signal and an audio signal which are in turn inputted to thecompression circuits 22 and 23, respectively. The video signal isbit-compressed through, for example, discrete cosine conversion. Theaudio signal is bit-compressed through, for example, non-linearquantization or differential PCM. As a result, the transmission rate ofthe video signal and the audio signal in total is reduced to, forexample, one twentieth.

Output signals of the compression circuits 22 and 23 are inputted to theparity addition circuit 24 for performing a signal processing whichincludes adding a parity signal for error correction and outputting thevideo signal and the audio signal serially in accordance with atransmission format. A serial output signal of the parity additioncircuit 24 is inputted to the modulation circuit 25. In the modulationcircuit 25, the serial signal is modulated in accordance with thecharacteristic and the frequency band of the transmission path 27. Forexample, in the case where the signal is transmitted in an electric waveform, quadruple phase shift keying (QPSK) is made. The modulated signalis inputted to the transmission circuit 26 from which it is outputted tothe transmission path 27.

As apparent from the foregoing explanation of the operation of thetransmission signal processing system, it is possible to transmit asignal at a speed which is ten times as high as a normal speed.

The above embodiment has been shown in conjunction with the case where asignal from the VTR is reproduced. However, a signal source is notlimited to the VTR and may include a magnetic disk device, an opticaldisk device or the like.

Next, explanation will be made of the operation of the VTR for receivingand recording the transmitted signal. The signal transmitted from thetransmission signal processing system is received by the receptioncircuit 30. The received signal is inputted to the demodulation circuit31. The demodulation circuit 31 is provided corresponding to themodulation, as provided by the modulation circuit 25, such as QPSKmodulation, for example, and demodulates the modulated signal to theoriginal signal. The demodulated signal is inputted to the errorcorrection circuit 32 in which the detection of and the correction foran error produced in the transmission path 27 are made on the basis ofthe parity signal added by the parity addition circuit 24. At this time,in the case where the S/N ratio of the transmission system is notsufficient so that complete correction for the error is impossible,correction is made through, for example, signal replacement, by use ofthe signal correlation.

An output signal of the error correction circuit 32 is inputted to theparity addition circuit 33. In the parity addition circuit 33, a paritysignal for detecting an error produced in a recording/reproducingprocess and making correction for the error is added. The parity-addedsignal is inputted to the modulation circuit 34. In the modulationcircuit 34, the signal is modulated to scrambled NRZ code, M² code orthe like as mentioned above. The modulated signal is recorded on themagnetic tape 40 by the magnetic heads 41 and 42 mounted on the cylinder43.

Since the signal supplied to the magnetic heads 41 and 42 is a signalwhich is time-base compressed to one tenth as compared with a signalupon normal operation, the servo control circuit 50 controls thecylinder 43 and the capstan 44 so that the rotation frequency of thecylinder 43 and the travel speed of the magnetic tape 40 become tentimes as high as those upon normal recording. Also, in order to record apredetermined signal at a predetermined position on the magnetic, tape40, synchronization information is detected from the received signal tocontrol the phase of rotation of the cylinder 41 on the basis of thedetected synchronization information.

Next, the operation of the VTR for reproducing the thus recorded signalwill be explained. Upon reproduction, the travel speed of the magnetictape 40 and the rotation frequency of the cylinder 43 are set to thoseupon normal reproduction. The reproduced signal is inputted to thedemodulation circuit 60. The demodulation circuit 60 is providedcorresponding to the modulation circuit 34 and demodulates the modulatedsignal. The demodulated signal is inputted to the error correctioncircuit 61 in which the detection of an error produced in the magneticrecording/reproducing system and the correction for the error are madeon the basis of the parity signal added by the parity addition circuit33. In the case where there is an error which cannot be corrected, theerror is properly corrected by use of the signal correlation. Also, thesignal is outputted after having been separated into a video signal andan audio signal.

The video signal is inputted to the expansion circuit 62. The expansioncircuit 62 is provided corresponding to the compression circuit 22 andrestores the compressed video signal into the original video signal. Anoutput signal of the expansion circuit 62 is inputted to the D/Aconversion circuit 64 and is converted thereby into an analog videosignal which is in turn outputted from the terminal 70.

The audio signal is inputted to the expansion circuit 63. The expansioncircuit 63 is provided corresponding to the compression circuit 23 andrestores the compressed audio signal into the original audio signal. Anoutput signal of the expansion circuit 63 is inputted to the D/Aconversion circuit 65 and is converted thereby into an analog audiosignal which is in turn outputted from the terminal 71.

In the foregoing, the embodiment of the present invention has been shownand the operation thereof has been explained. According to the presentinvention, a video signal and an audio signal over a long time can betransmitted and recorded in a short time, thereby making it possible toextend the range of use of the digital VTR.

Another embodiment of the present invention is shown in FIG. 2. FIG. 2is partially similar to FIG. 1. The same parts in FIG. 2 as those inFIG. 1 are denoted by the same reference numerals as those used in FIG.1 and detailed explanation thereof will be omitted. The embodiment shownin FIG. 2 concerns a VTR in which a signal transmitted/received at ahigh speed can be recorded while being monitored.

In FIG. 2, reference numeral 80 denotes a change-over switch, numeral 81an error correction circuit, and numeral 82 a memory circuit. An errorcorrected video signal outputted from the error correction circuit 81 isinputted through the memory circuit 82 to a terminal R side of thechange over switch 80 which is selected upon recording. The memorycircuit 82 has a memory capacity for at least one field. The videosignal received at a high speed is stored into a memory of the memorycircuit 82 with the number of frames being reduced. The stored signal isread from the memory at a normal speed and is inputted to an expansioncircuit 62.

Upon reproduction, a video signal output of an error correction circuit61 is inputted to a terminal P side of the change-over switch 80 whichis selected upon reproduction. Accordingly, the operation of theembodiment of FIG. 2 upon reproduction is similar to that of theembodiment shown in FIG. 1.

In the embodiment shown in FIG. 2, upon recording, the video signaloutputted from the error correction circuit 81 is inputted to theexpansion circuit 62 through the memory circuit 82. Alternatively, anoutput signal of a modulation circuit 34 may be inputted to ademodulation circuit 60 through a memory circuit. Also, in the casewhere the operating speed of the demodulation circuit 60 or the errorcorrection circuit 61 leaves a margin, a memory circuit may be properlyplaced at a post stage. Or, in the case where the storage capacity ofthe error correction circuit 61 or the expansion circuit 62 leaves amargin, the circuit may be used as a memory circuit or any additionalmemory circuit may be omitted.

As has been explained in the above, the embodiment shown in FIG. 2 makesit possible to record a received video signal while monitoring it in theform of a picture having a reduced number of frames.

In the embodiment shown in FIG. 1, the parity signal is added in orderto make the detection of and the correction for an error which may beproduced in the transmission system or the magneticrecording/reproducing system. One example of a parity adding method isshown in FIG. 3 in conjunction with the case of a D2 format VTR. In theD2 format VTR, a signal for one field is divided into a plurality ofsegments for signal processing. FIG. 3 shows one segment. In FIG. 3,reference numeral 90 represents a group of video data, numeral 91 agroup of outer code parities, and numeral 92 a group of inner codeparities. Firstly, outer code parities are added for data of thematrix-like arranged video data group 90 which lie in a verticaldirection in FIG. 3. Thereafter, inner code parities are added for dataof the video data group 90 and the outer code parity group 91 lying in ahorizontal direction in FIG. 3, thereby producing a signal to berecorded. Though detailed explanation of the generation of parities willbe omitted herein, the parities are generated in accordance with agenerating function G(x).

In the embodiment shown in FIG. 1, if the same parity generation manneris employed by the parity addition circuits 24 and 33, the errorcorrection circuits 32 and 61 may hold the most part thereof in common.Namely, since the error correction circuits 32 and 61 are circuits whichare respectively used upon recording and upon reproduction, it ispossible to reduce the circuit scale or size by using the most part ofthe circuits 32 and 61 in common.

Further, in the case where the same parity generation manner is employedby the parity addition circuits 24 and 33 in the embodiment shown inFIG. 1, it is possible to further reduce the circuit scale or-size ofthe recording/reproducing system. The construction in that case is shownin FIG. 4 as still another embodiment of the present invention. FIG. 4is partially common to FIG. 1 or 2. The parts in FIG. 4 common to thosein FIG. 1 or 2 are denoted by the same reference numerals as those usedin FIG. 1 or 2 and detailed explanation thereof will be omitted.

The embodiment shown in FIG. 4 is based on a concept that an errorproduced in a transmission system and an error produced in a magneticrecording/reproducing system are simultaneously detected and correctedby an error correction circuit 61. Accordingly, a signal received by areception circuit 30 is demodulated by a demodulation circuit 31 and isinputted to a modulation circuit 34 without being subjected to errorcorrection and parity addition. The subsequent processing is the same asthat in the embodiment shown in FIG. 1 or 2. Namely, a reproduced signalis inputted to the error correction circuit 61 after demodulation by ademodulation circuit 60. As mentioned above, an error produced in thetransmission system and an error produced in the magneticrecording/reproducing system are simultaneously detected and correctedby the error correction circuit 61 in the reproducing system.

In the embodiment shown in FIG. 4, the error correction circuit 32 andthe parity addition circuit 33 can be removed as compared with theembodiment shown in FIG. 1 or 2, thereby making it possible to reducethe circuit scale.

Though having not been mentioned in the foregoing embodiments, in ahelical scan VTR as shown, since a signal becomes discontinuous when atrack jump is made upon reproduction, the recording is made with anamble signal being added to the heading portion of a signal. Since theaddition of an amble signal is employed in the D2 format VTR, detailedexplanation thereof will be omitted. Also, in order to define a startingposition of a signal, a synchronizing signal is properly added. Sincethe addition of a synchronizing signal is known in, for example, the D2format VTR, detailed explanation thereof will be omitted.

In the embodiment shown in FIG. 1, the addition of an amble signal maybe made by the parity addition circuit 24. Alternatively, it may be madeon the recording/reproducing system side in order to enhance theefficiency of use of the transmission path 27. In this case, theaddition of an amble signal can be made by the parity addition circuit33. As for the embodiment shown in FIG. 4, in the case where theaddition of an amble signal is to be made on the recording/reproducingsystem side, the amble signal can be added by the modulation circuit 34.In the case where the addition of an amble signal is made on therecording/reproducing system side, it is possible to enhance theefficiency of use of the transmission path 27. On the other hand, in thecase where the addition of an amble signal is made on the transmissionsignal processing system side, the lowering of the cost of a VTR can beattained as a great effect when a signal is sent to a multiplicity ofVTR's simultaneously.

FIG. 5 shows a further embodiment of the present invention in which thefurther reduction of the circuit scale of a VTR on the receiving sideand hence the further lowering of the cost can be attained in the casewhere a signal is sent to a multiplicity of VTR's simultaneously.

FIG. 5 is partially common to FIG. 1, 2 or 4. The parts in FIG. 5 commonto those in FIG. 1, 2 or 4 are denoted by the same reference numerals asthose used in FIG. 1, 2 or 4 and detailed explanation thereof will beomitted. In FIG. 5, reference numeral 100 denotes a modulation circuit.The embodiment shown in FIG. 5 is based on a concept that a signalprocessing required upon a recording mode of a VTR is performed on thetransmitting side. Namely, modulation adapted for magneticrecording/reproduction, for example, a signal processing correspondingto the modulation circuit 34 shown in FIG. 4 is performed on thetransmission signal processing system side. After parities have beenadded by a parity addition circuit 24 of the transmission signalprocessing system, the modulation adapted for the magneticrecording/reproduction is performed by the modulation circuit 100.Therefore, modulation adapted for transmission is performed by amodulation circuit 25. As a modulation system employed by the modulationcircuit 100 is suitable a system which does not cause the extension of afrequency band by modulation, for example, scrambled NRZ. A signalmodulated by the modulation circuit 25 is transmitted to a transmissionpath 27 through a transmission circuit 26 in a manner to that in theembodiment shown in FIG. 1.

The signal received by a reception circuit 30 through the transmissionpath 27 is inputted to a demodulation circuit 31 in which the signal issubjected to demodulation corresponding to the modulation circuit 25.Since the signal demodulated by the demodulation circuit 31 is one whichhas already been subjected by the modulation circuit 10 to themodulation adapted for the magnetic recording/reproduction, the signalis recorded on a magnetic tape 40 by magnetic heads 41 and 42 as it is.As a result, the same recording as that in the embodiment shown in FIG.4 is made. An operation upon reproduction is similar to that in theembodiment shown in FIG. 4.

As apparent from the above, the present embodiment makes it possible toremarkably reduce the circuit scale of the VTR.

According to one of applications of the present invention, it ispossible to transmit a signal from a transmission signal processingsystem to a multiplicity of VTR's through a transmission pathsimultaneously and at a high speed, as has already been mentioned. Inthis case, it is difficult to control a multiplicity of VTR'ssimultaneously. Further, it is required to make a control which causesspecified ones of the VTR's to perform recording operations andspecified others of the VTR's not to perform recording operations. Atechnique for realizing such a control will be shown just below.

For the above purpose, control signals are transmitted prior totransmission of a signal to be recorded. One example of the controlsignals is shown in FIG. 6. In the figure, reference numeral 110 denotesa synchronizing signal, numeral 111 an ID signal indicative of a controlto be made, numeral 112 an address signal indicative of a VTR to becontrolled, numeral 113 a control signal for bringing a VTR designatedby the address signal 112 into a recording mode, numeral 114 a controlsignal for stopping the recording, numerals 115 and 116 blank signals,and numeral 120 a recording signal to be actually recorded.

The ID signal 111 indicating the transmission of the address signals 112indicative of VTR's in which a signal is to be recorded, is transmittedat a predetermined position relative to the synchronizing signal 110 tobring each VTR into a standby condition. After all the address signalshave been transmitted, the ID signal 113 is transmitted to start therecording of the signal 120 in the designated VTR's. After the signal120 has been transmitted, the ID signal 114 to control the stop ofrecording is transmitted. Each of the blank signals 115 and 116 is asignal for conforming a signal transmission format to the othertransmission signal and is therefore an insignificant signal portion.

In the embodiments shown in FIGS. 1 and 5, those control signals areproduced by a control signal generation circuit 130 and are transmittedwith parities which are added by the parity addition circuit 24 formaking correction for an error produced during transmission.

In the VTR shown in FIG. 1, the control signals are detected by acontrol circuit 131 after the reception by the reception circuit 30, thedemodulation by the demodulation circuit 31 and the correction by theerror correction circuit 32 for an error produced during transmission tomake a control for the recording and the stop of recording in therecording/reproducing system.

In the case of the VTR's shown in FIGS. 4 and 5, an output signal of thedemodulation circuit 31 is inputted to the error correction circuit 61for a need of making correction for an error produced duringtransmission and error-corrected control signals are inputted to acontrol circuit 131. In a change-over circuit 132, the terminal R sidefor selecting an output signal of the demodulation circuit 31 isselected upon recording and the terminal P side for selecting an outputsignal of the demodulation circuit 60 is selected upon reproduction.

As apparent from the foregoing, the present embodiment makes it possibleto control a multiplicity of VTR's selectively and simultaneously.

Also, the use of the change-over circuit 132 and a memory circuit makesit possible to record a signal while monitoring it in the form of apicture having a reduced number of frames, as explained in conjunctionwith the embodiment shown in FIG. 2.

Next, a still further embodiment of the present invention will beexplained by use of FIG. 7. In the figure, reference numeral 301 denotesan input terminal for standard analog video signal, numeral 302 an inputterminal for standard digital video signal, numeral 303 an inputterminal for high-speed digital video signal, numeral 305 a recordingsystem mode change-over switch, numeral 306 a recording systemchange-over signal generation circuit, numeral 310 an A/D converter,numeral 320 a change-over circuit, numeral 330 a data compressioncircuit, numeral 340 a change-over circuit, numeral 350 a recordingsystem signal processing circuit for performing a signal processingwhich includes addition of error correction code and modulation forrecording, numeral 370 a cylinder, numeral 371 a magnetic tape, numerals372 and 372′ magnetic heads, numeral 380 a reproducing system signalprocessing circuit for performing a signal processing which includesdemodulation for reproduction, error detection and error correction.Numeral 390 a change-over circuit, numeral 400 a data expansion circuit,numeral 420 a D/A converter, numeral 431 an output terminal for standardanalog video signal, numeral 432 an output terminal for standard digitalvideo signal, numeral 433 an output terminal for high-speed digitalvideo signal, numeral 435 a reproducing system mode change-over switch,and numeral 436 a reproducing system change-over signal generationcircuit.

The present embodiment is an example of a digital magneticrecording/reproducing system which has recording modes of standard-speedrecording and high-speed recording and reproduction modes ofstandard-speed reproduction and high-speed reproduction. FIG. 8 showsone example of the specification of input video signals.

Firstly, explanation will be made of standard-speed recording. A digitalsignal into which an analog video signal inputted from the inputterminal 301 is converted by the A/D converter 310 or an equivalentdigital signal which is inputted from the input terminal 302, isswitched or selected by the change-over circuit 320, is subjected to apredetermined data compression processing by the data compressioncircuit 330 and is thereafter inputted to a terminal 340 a of thechangeover circuit 340. In the change-over circuit 340, a change-over toconnect the terminal 340 a and a terminal 340 c is made by a change-oversignal from the recording system change-over signal generation circuit306. Thereby, the data-compressed signal is inputted to the recordingsystem signal processing circuit 350. In the recording system signalprocessing circuit 350, a signal processing such as channel division,addition of error correction code and modulation for recording isperformed at a predetermined processing clock adapted for thedata-compressed signal. Thereafter, the signal is supplied to themagnetic heads 372 and 372′ mounted on the cylinder 370 so that it isrecorded onto the magnetic tape 371. The cylinder 370 and the magnetictape 371 are controlled by a servo control circuit 360. The servocontrol circuit 360 controls a cylinder motor and a capstan motor so asto provide a cylinder rotation speed and a tape speed for standard speedand so as to be synchronized with the input video signal.

Next, explanation will be made of high-speed recording. A high-speeddigital video signal inputted from the input terminal 303 is sent to aterminal 340 b of the change-over circuit 340. Since the high-speeddigital video signal is a signal which has already been subjected to adata compression processing, it is not necessary to pass the signalthrough the data compression circuit 330. A change-over to connect theterminal 340 b and the terminal 340 c is made by a change-over signalfrom the recording system change-over signal generation circuit 306 sothat the high-speed digital video signal is inputted to the recordingsystem signal processing circuit 350. In the recording system signalprocessing circuit 350, a signal processing similar to that in the caseof the standard-speed recording is performed at a predeterminedprocessing clock adapted for the high-speed digital video signal.Thereafter, the signal is supplied to the magnetic heads 372 and 372′mounted on the cylinder 370 so that it is recorded onto the magnetictape 371. The cylinder 370 and the magnetic tape 371 are controlled bythe servo control circuit 360. The servo control circuit 360 control thecylinder motor and the capstan motor so as to provide a predeterminedcylinder rotation speed and a predetermined tape speed and so as to besynchronized with the input video signal.

In the present invention, the recording onto the tape can be made withthe quite same format in both the standard-speed recording and thehigh-speed recording, thereby making it possible to greatly shorten arecording time in the high-speed recording mode.

Next, explanation will be made of a signal processing upon reproduction.In the present embodiment, the recording pattern on the magnetic tape isthe same whichever of the standard-speed recording and the high-speedrecording is selected as a recording mode. Therefore, eitherstandard-speed reproduction or high-speed reproduction can be selectedirrespective of the recording mode.

Firstly, the standard-speed reproduction will be explained. The servocontrol circuit 360 controls the cylinder motor and the capstan motor sothat a cylinder rotation speed and a tape speed for standard speed areprovided. A signal reproduced by the magnetic heads 372 and 372′ isinputted to the reproducing system signal processing circuit 380. In thereproducing system signal processing circuit 380, a signal processingsuch as demodulation for reproduction, channel synthesis, errordetection and error correction is performed at a predeterminedprocessing clock adapted for the standard-speed reproduction.Thereafter, the signal is supplied to a terminal 390 a of thechange-over circuit 390. In the change-over circuit 390, a changeover toconnect the terminal 390 a and a terminal 390 c is made uponstandard-speed reproduction by a change-over signal from the reproducingsystem change-over signal generation circuit 436. Thereby, thereproduced signal is supplied to the data expansion circuit 400. In thedata expansion circuit 400, a signal processing reverse to the datacompression processing upon recording is performed so that the signal isrestored to the original signal. Thereby, the original transmission rateis restored. The data-expanded reproduction signal is sent to the D/Aconverter 420 on one hand to be outputted as an analog video signal fromthe output terminal 431 after D/A conversion and is sent to the outputterminal 432 on the other hand to be outputted as a digital video signaltherefrom.

Next, explanation will be made of the high-speed reproduction. The servocontrol circuit 360 controls the cylinder motor and the capstan motor sothat a predetermined cylinder rotation speed and a predetermined tapespeed adapted for the high-speed reproduction are provided. A signalreproduced by the magnetic heads 372 and 372′ is inputted to thereproducing system signal processing circuit 380. In the reproducingsystem signal processing circuit 380, a signal processing such asdemodulation for reproduction, channel synthesis, error detection anderror correction is performed at a predetermined processing clocksadapted for the high-speed reproduction. Thereafter, the high-speedreproduction signal is supplied to the terminal 390 a of the change-overcircuit 390. In the change-over circuit 390, a change-over to connectthe terminal 390 a and a terminal 390 b is made upon high-speedreproduction. Thereby, the high-speed digital video signal is outputtedfrom the output terminal 433.

A furthermore embodiment of the present invention will be explained byuse of FIG. 9. The construction of the present embodiment is similar tothat of the embodiment shown in FIG. 7 but is different therefrom inthat the change-over circuit 340 is placed at a different position, thechange-over circuit 390 used in FIG. 7 is eliminated and a change-overcircuit 345 is newly added.

An input/output signal upon standard-speed recording/reproduction in thepresent embodiment is the same as that in the embodiment shown in FIG.7. As for high-speed recording and high-speed reproduction, however, thepresent embodiment is different from the embodiment of FIG. 7 in thatthe transmission of a high-speed digital video signal is made in theform of a recording format. Accordingly, upon high-speed recording, thehigh-speed digital video signal is not passed through a recording systemsignal processing circuit 350 but is recorded onto a tape through thechange-over circuit 340 as it is. Upon high-speed reproduction, areproduced signal is subjected to a signal processing for reproductionsuch as error detection and error correction by a reproducing systemsignal processing circuit 380 and is thereafter inputted to a terminal345 b of the change-over circuit 345. The signal supplied through thechange-over circuit 345 to the recording system side signal processingcircuit 350 is subjected to a signal processing for recording such asaddition of error correction code and modulation for recording by thesignal processing circuit 350 to form a recording format and isthereafter outputted as a high-speed digital video signal from an outputterminal 433.

The embodiments shown in FIGS. 7 and 9 have feature that high-speedrecording and high-speed reproduction are possible. The best use of thisfeature can be made for dubbing or data communication with the result ofeffective shortening of a dubbing time, a data communication time or adata circuit line occupation time. Also, though those embodiments havebeen mentioned in conjunction with an example in which all ofstandard-speed recording, high-speed recording, standard-speedreproduction and high-speed reproduction modes are involved, it is notnecessarily required to implement all of those modes. There may beconsidered an example in which only a necessary mode is provided incompliance with the purpose of use. FIG. 10 shows an embodiment in whicha high-speed recording function is provided as a recording mode and atleast a high-speed reproduction function is provided as a reproductionmode. Also, there may be considered an embodiment as a system for theexclusive use for reproduction in which at least a high-speedreproduction function is provided, as shown in FIG. 11. Further, FIG. 12shows an embodiment in which a high-speed recording function is providedas a recording mode and a standard-speed reproduction function isprovided as a reproduction mode.

FIG. 13 is a block diagram of one example of the magneticrecording/reproducing system of the embodiment of FIG. 7 for explainingprocessings subsequent to the compression processing. In FIG. 13,reference numeral 201 denotes a synchronization detection circuit,numeral 204 a recording modulation circuit, numeral 205 a cylinder servocontrol circuit, numeral 206 a capstan servo (or tape speed) controlcircuit, numeral 207 a reproduction reference signal generation circuit,numeral 210 a demodulation circuit, numeral 211 a cylinder, numeral 212a pair of recording heads, numeral 213 a pair of reproducing heads,numeral 214 a capstan which controls the tape speed, numeral 215 amagnetic tape, numeral 216 a delivery reel, and numeral 217 a take-upreel. FIG. 14 is a timing chart of input and output signals in theexample shown in FIG. 13 and schematically illustrate a compressedpicture signal 251 which is an input signal, a synchronizing signal 252of the picture signal, a standard-speed reproduction signal 255 which isan output signal, and a reproduction synchronizing signal 256.

In the shown example, n-tuple speed recording is realized by making atape speed and a cylinder rotation speed upon recording ntimes as highas those upon standard-speed reproduction. As shown in FIG. 14, thecompressed video signal as an input signal of the circuit shown in FIG.13 and the synchronizing signal include information 251 for n picturesand n synchronizing pulses 252 synchronous therewith in a time when onepicture is reproduced at a standard speed. The picture information isconverted into a predetermined recording format by the recordingmodulation circuit 204 and is recorded onto the magnetic tape 215 by therecording heads 212. At this time, a synchronizing signal for thecylinder servo control circuit 205 and the capstan-servo control circuit206 is increased by n times in compliance with the n-tuple speed videosignal, as shown by 252 in FIG. 14, so that the rotation speed of thecylinder 211 and the feed speed of the magnetic tape 215 are increasedby n times. Thereby, the recording onto the tape can be made with thequite same recording format as that in the case of the standard-speedrecording. Upon reproduction, a synchronizing signal for the cylinderservo control circuit 205 and the capstan servo control circuit 206 issupplied from the reproduction reference signal generation circuit 207to restore the cylinder rotation speed and the tape feed speed to thoseupon standard-speed reproduction, and a signal read by the reproducingheads 213 is demodulated by the demodulation circuit 210 and isoutputted therefrom. In the circuit shown in FIG. 13, if the input videosignal and the synchronizing signal are ones of standard speed,standard-speed recording is possible. Also, n-tuple speed reproductionis possible if the frequency of an output signal from the reproductionreference signal generation circuit is increased by n times.

FIG. 15 is a block diagram of another example of the magneticrecording/reproducing system of the embodiment of FIG. 7 for explainingprocessings subsequent to the compression processing. FIG. 16 is atiming chart of input and output signals in the example shown in FIG.15. In FIG. 15, the same reference numerals as those used in FIG. 13denote the same or equivalent components as or to those shown in FIG.13. In FIG. 15, reference numeral 202 denotes a ÷m circuit, numeral 203recording system memories, numeral 208 a ÷m circuit, and numeral 209reproducing system memories. In FIG. 16, the same reference numerals asthose used in FIG. 14 denote the same or equivalent signals as or tothose shown in FIG. 14. In FIG. 16, reference numeral 253 denotesoutputs of the recording system memories 203 and numeral 254 denotes anoutput of the ÷m circuit 208 or a synchronizing signal divided by m.

The embodiment shown in FIG. 15 is an example in which m pairs ofrecording heads are used to simultaneously record magnetic signals for mpictures on m tracks, thereby realizing high-speed recording whilesuppressing an increase in the cylinder rotation speed. Uponreproduction, m pairs of reproducing heads are used. Though FIG. 15shows the case where two pairs of recording heads 212 are used tosimultaneously record information for two pictures on two tracks, threeor more pairs of heads can be used in a similar manner.

FIG. 17 is a table showing some examples of the tape speed and thecylinder rotation speed (rpm) in the embodiments shown in FIGS. 13 and15. In the table, high-speed recording or reproduction at a speed tentimes as high as the standard speed is shown by way of example. Designfor implementing another high-speed recording or reproduction issimilarly possible. In the table shown in FIG. 17, examples ({circlearound (1)}, {circle around (2)} and {circle around (3)} correspond tothe embodiment shown in FIG. 13 and examples {circle around (4)} and{circle around (5)} correspond to the embodiment shown in FIG. 15.

A still furthermore embodiment of a digital signal recording/reproducingsystem of the present invention will be explained by use of a blockdiagram shown in FIG. 18.

In FIG. 18, reference numeral 501 denotes a signal input terminal towhich a plurality of video signals are inputted in a time-divisionmultiplex form, numeral 502 a recording selection signal-input terminalto which a recording selection signal for selecting one or pluralsignals to be recorded from the multiplexed input signal is inputted,numeral 503 a recording signal selection circuit for selecting thesignals to be recorded from the multiplexed input signal in accordancewith the recording selection signal from the input terminal 502, numeral504 a recording signal processing circuit for subjecting the selectedsignals to a digital processing for recording onto a recording medium,numerals 505 and 505′ magnetic heads, numeral 506 a rotating drum,numeral 507 a magnetic tape or the recording medium, numeral 508 a servocircuit for controlling the rotation of the drum 506 and the travel ofthe tape 507, numeral 511 a reproduction selection signal input terminalto which a reproduction selection signal for selecting one or pluralsignals to be outputted as a reproduction signal from among themultiple-recorded and reproduced signals is inputted, numeral 509 areproduction signal selection circuit for selecting the signals to beoutputted as a reproduction signal from among the multiple-recorded andreproduced signals in accordance with the reproduction selection signalfrom the input terminal 511, numeral 510 a reproduction signalprocessing circuit for subjecting the selected signals to a digitalprocessing, and numeral 512 a reproduction signal output terminal.

The time-division multiplexed input video signal from the signal inputterminal 501 is supplied to the recording signal selection circuit 503.The recording signal selection circuit 503 is also supplied with therecording selection signal from the recording selection signal inputterminal 502 to make the selection of signals to be recorded. Forexample, in the case where six kinds of video signals A, B, C, D, E andF are inputted in a time-division multiplex form as shown in (a) of FIG.19 and four signals A, B, C and D thereof are to be selected andrecorded, an output of the recording signal selection circuit 503 is asshown in (b) of FIG. 19. Such an output signal of the recording signalselection circuit 503 is inputted to the recording signal processingcircuit 504 which in turn performs a signal processing for recordingsuch as addition of error correction code. Also, the recording signalselection circuit 503 produces a speed control signal on the basis ofthe number of signals in the time-division multiplexed input videosignal, the transmission rate of the input signal and the number ofsignals to be recorded which are selected by the recording selectionsignal. The speed control signal is supplied to the recording signalprocessing circuit 504 and the servo circuit 508. For example, in thecase where the input video signal is time-division multiplexed tosextuplet with each of six signals in the multiplexed input signal beingtransmitted at a rate time-base compressed to ⅙ and four signals amongthe six signals in the multiplexed input signal are to be selectivelyrecorded, a signal indicative of a quadruple speed is produced as thespeed control signal. Also, in the case where the input video signal istime-division multiplexed to sextuplet with each of six signals in themultiplexed input signal being transmitted at a rate time-basecompressed to 1/12 and four signals among the six signals in themultiplexed input signal are to be selectively recorded, a signalindicative of a octuple speed is produced as the speed control signal.Namely, in the case where an input signal is multiplexed to N-plet, thecompression rate of each of the N signals in the multiplexed inputsignal is 1/K and the number of signals to be selectively recorded is L,a speed control signal indicative of an (L×K)/N-tuple speed is produced.The operating speed of the recording signal processing circuit 504 whichprocesses a signal from the recording signal selection circuit 503, ischanged in accordance with the speed control signal. For example, in thecase of a speed control signal indicative of a quadruple speed, therecording signal processing circuit 504 performs a signal processing ata speed four times as high as a normal speed and supplies the processedsignal to the magnetic heads 505 and 505′. Here, for example, in thecase where the input video signal is time-division multiplexed tosextuplet with each of the six signals in the multiplexed input signalbeing transmitted at a rate time-base compressed to ⅙ and a speedcontrol signal indicative of a quadruple speed is used to selectivelyrecord four signals from among the six signals, the speed of an inputsignal inputted to the recording signal processing circuit 504 is fourtimes as high as that of one video signal having a normal speed and therecording signal processing circuit 504 processes this quadruple-speedinput signal at a quadruple speed and supplies the processed signal tothe magnetic heads, thereby making it possible to record all of the fourselected signals. Also, if the recording signal selection circuit 503 isconstructed so that signals to be selectively recorded are sequentiallychanged for every one track on the tape, compatibility can be held inregard to the number of signals to be selectively recorded and aprocessing speed by causing the recording signal processing circuit 504to perform a completed processing for every one track. In the following,explanation will be made in conjunction with the case where each videosignal is recorded in such a form completed for every track. However, itshould be noted in advance that the present invention is applicable toanother recording system, for example, a system in which signals arerecorded in a form changed for every pixel, line or field. On the otherhand, the servo circuit 508 supplied with the speed control signalindicative of the quadruple speed controls the rotation speed of therotating drum 506 so that it becomes four times as high as a normalspeed and the travel speed of the magnetic tape 507 so that it becomesfour times as high as a normal speed. Thereby, four signals A, B, C andD are alternately recorded on successive tracks of the magnetic tape507, as shown in FIG. 20. According to the control mentioned above, thepattern of recording tracks on the tape becomes the same irrespective ofthe number of signals in the multiplexed input signal, the transmissionrate of each signal and the number of signals to be selectivelyrecorded. In order to make a control upon reproduction easy, it ispreferable that the number of selectively recorded signals and theidentification codes or signal numbers thereof (for example, A, B, C andD or 0, 1, 2 and 3) are recorded as an ID signal for every track.

In the above example, the recording of the time-division multiplexedsignal has been mentioned. However, it is needless to say that thepresent invention is also applicable to the case where the number ofmultipet signal components in an input video signal is 1 or the inputvideo signal is not multiplexed. In such a case, since the recordingsignal processing circuit 504 and the servo circuit 508 operate atspeeds proportional to the transmission rate of the input video signal,an effect is manifested, for example, in high-speed dubbing. As apparentfrom the foregoing explanation of the operation, it is of course that amultiplexed signal can be recorded at a high speed.

Upon reproduction, a signal reproduced from the magnetic tape 507 by themagnetic heads 505 and 505′ mounted on the rotating drum 506 is inputtedto the reproduction signal selection circuit 509. The reproductionsignal selection circuit 509 produces a speed control signal, forexample, by detecting the number of multiple-recorded signals from theID signal included in the reproduced signal and sends the speed controlsignal to the servo circuit 508. The speed control signal is a signalindicative of a speed four times as high as the normal reproductionspeed in the case where the number of multiple-recorded signals is 4 anda signal indicative of a sextuple speed in the case where it is 6. Inthe case of the quadruple speed, the servo control circuit 508 suppliedwith the speed control signal indicative of the quadruple speed controlsthe rotation speed of the rotating drum 506 so that it becomes fourtimes as high as a normal speed and the travel speed of the magnetictape 7 so that it becomes four times as high as a normal speed. Thereby,there can be traced all of signals recorded so that the recording trackpattern on the tape becomes the same irrespective of the number ofsignals to be selectively recorded. In a system which has not a signalindicative of the number of selectively recorded signals, there may beemployed a method in which the speed control signal is manually set. Ina system in which the number of signals to be recorded on the tape isfixed, the speed control signal has a fixed value. The reproductionsignal selection circuit 509 receives a reproduction selection signalinputted from the reproduction selection signal input terminal 511 toselect a desired signal(s) from among the signals reproduced by themagnetic heads 505 and 505′ and to output the selected signal as areproduction signal to the reproduction signal processing circuit 510.The reproduction signal selection circuit 509 also outputs a selectionnumber signal indicative of the number of selected signals to thereproduction signal processing circuit 510.

The reproduction signal processing circuit 510 performs a signalprocessing such as code error correction processing and picture signalprocessing for the reproduction signal at a processing speedcorresponding, to the selection number signal and outputs the processedreproduction signal from the output terminal 512. For example, in thecase where the number indicated by the selection number signal is 2, thesignal processing speed is two times as high as a normal speed andvarious processings are performed for each selected signal. For example,in the case where signals A and C are selected, the signals A and C areoutputted alternately for each field. In the case where the numberindicated by the selection number signal is 1, for example, when thereproduction selection signal from the reproduction selection signalinput terminal 511 selects only the signal C, the reproduction signalprocessing circuit 510 performs the signal processing at the normalspeed to output the signal as reproduced at a normal speed. As apparentfrom the above, the present embodiment makes it possible tosimultaneously record any number of signals selected from among aplurality of signals in a multiplexed video signal and to simultaneouslyreproduce any number of signals from among the recorded signals.

In the case where a plurality of signals are simultaneously reproduced,a construction for outputting the reproduced signals from separateoutput terminals simultaneously and in parallel may be employed,particularly, in the case of an analog output, as a method other thanthe construction in which the plurality of reproduced signals areoutputted in a time-division multiplex form, as mentioned above. Thoughin the above-mentioned example the reproduction signal is outputted at areproduction speed for a usual video signal, the transmission rate ofthe reproduction signal may be made higher than the reproduction speedfor the usual video signal in order to transmit the reproduction signalto another system in an analog or digital signal form at a high rate orto perform high-speed dubbing which is one of effects of the presentembodiment. This can be realized in such a manner that the fundamentaloperating speed of there producing system is set to be higher than anormal reproduction speed and the operating speeds of the servo circuit508, the reproduction signal selection circuit 509 and the reproductionsignal processing circuit 510 are changed in accordance with the numberof multiple-recorded signals and/or the number of signals to beoutputted as a reproduction signal with the above fundamental speedbeing the standard. If the transmission rate of a reproduction signal ismade variable so that a rate adapted for a transmission path to whichthe reproduction signal is to be connected or the performance orfunction of a recorder by which the reproduction signal is to berecorded, can be selected.

As mentioned above, according to the present embodiment, it is possibleto simultaneously record any number of signals selected from among aplurality of signals in a multiplexed video signal and to reproduce anynumber of signals from among the recorded signals at any speed. Also, inthe case where a plurality of signals are selected and reproduced andthe plurality of reproduced signals are simultaneously outputted in atime-division multiplex form or from separate output terminals inparallel, it is possible to arbitrarily set the transmission rate of anoutput signal.

The present embodiment has been explained in conjunction with the casewhere the present invention is applied to a helical-scandigital-recording VTR. It is of course that a similar effect can beobtained in the case where the present invention is applied to a fixedhead VTR. The fixed head system is convenient for the structuring of asystem since it has a higher degree of freedom for the setting of theunits of division of a signal subjected to time-division multiplerecording as compared with the helical scan system. Also, it is ofcourse that the present invention is applicable to arecording/reproducing equipment other than the VTR or is applicable to adigital signal processing and analog recording system.

The present invention can be applied to not only the case where an inputsignal is time-division multiplexed, as mentioned above, but also thecase where a plurality of signals are inputted simultaneously and inparallel. In the latter case, the recording signal selection circuit 503is constructed to receive the input signals in parallel.

As has been mentioned in the foregoing, according to the presentinvention, it is possible to realize a digital VTR in which high-speedrecording onto a tape can be made with the same format as that used instandard-speed reproduction. Further, there can be realized atransmission signal processing for transmitting at a high rate a videosignal to be recorded by such a digital VTR. Also, in the case where asignal transmitted from the transmission signal processing system is tobe recorded by a multiplicity of VTR's, it is possible to designatethose ones of the multiplicity of VTR's by which recording is to be madeand to make a control of the start/stop of recording.

1. An apparatus for receiving digital information including at least oneof digital video information and digital audio information, comprising:a receiver which receives the digital information that has digital videoinformation bit-compressed by a first compression system, digital audioinformation bit-compressed by a second compression system, anderror-detection information added to both the digital video informationand the digital audio information; a demodulator which demodulates thedigital information received by the receiver; an error detector whichdetects an error of digital information demodulated by the demodulatorby use of the error-detection information; a first expander whichbit-expands video information among the digital information errordetected by the error detector corresponding system; and a secondexpander which bit-expands audio information among the digitalinformation error detected by the error detector corresponding to thesecond compression system.
 2. An apparatus according to claim 1, whereinthe first compression system and the second compression system aredifferent systems.
 3. An apparatus according to claim 1, wherein thedemodulator affects QPSK demodulation.
 4. An apparatus according toclaim 1, further comprising; an output terminal which outputs thedigital information error-detected by the error detector to arecording/reproducing apparatus; an input terminal which inputs areproduced signal from the recording/reproducing apparatus; and aselector which selects one of the digital information error-detected bythe error detector and the digital information inputted from the inputterminal; wherein the digital information selected by the selector isbit-expanded by the first expander and the second expander.
 5. Anapparatus according to claim 1, wherein the first compression systemuses a discrete cosine transform, the received digital information isphase-modulated, and the demodulator demodulates the digital informationreceived by the receiver in accordance with the phase-modulation.
 6. Anapparatus for processing a transmitted digital signal including at leastone of a video signal and an audio signal, comprising: a receiver whichreceives the transmitted digital signal, wherein the transmitted digitalsignal includes a video signal bit-compressed by a first compressionmethod, an audio signal bit-compressed by a second compression method,and an error correction signal added commonly to both the video signaland the audio signal; a demodulator which demodulates the digital signalreceived by the receiver; an error corrector which corrects an error ofthe digital signal demodulated by the demodulator based on the errorcorrection signal; a first expander which bit-expands the video signalof the digital signal corrected by the error corrector in accordancewith the first compression method; and a second expander whichbit-expands the audio signal of the digital signal corrected by theerror corrector in accordance with the second compression method.
 7. Theapparatus according to claim 6, wherein the first compression methodutilizes a discrete cosine transform.